<template>
  <div class="s-canvas">
      <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>
<script>
export default {
  name: "SIdentify",
  props: {
      identifyCode: {
          type: String,
          default: "1234",
      },
      fontSizeMin: {
          type: Number,
          default: 16,
      },
      fontSizeMax: {
          type: Number,
          default: 40,
      },
      backgroundColorMin: {
          type: Number,
          default: 180,
      },
      backgroundColorMax: {
          type: Number,
          default: 240,
      },
      colorMin: {
          type: Number,
          default: 50,
      },
      colorMax: {
          type: Number,
          default: 160,
      },
      lineColorMin: {
          type: Number,
          default: 40,
      },
      lineColorMax: {
          type: Number,
          default: 180,
      },
      dotColorMin: {
          type: Number,
          default: 0,
      },
      dotColorMax: {
          type: Number,
          default: 255,
      },
      contentWidth: {
          type: Number,
          default: 112,
      },
      contentHeight: {
          type: Number,
          default: 38,
      },
  },
  methods: {
      // 生成一个随机数
      randomNum(min, max) {
          return Math.floor(Math.random() * (max - min) + min);
      },
      // 生成一个随机的颜色
      randomColor(min, max) {
          let r = this.randomNum(min, max);
          let g = this.randomNum(min, max);
          let b = this.randomNum(min, max);
          return "rgb(" + r + "," + g + "," + b + ")";
      },
      drawPic() {
          let canvas = document.getElementById("s-canvas");
          let ctx = canvas.getContext("2d");
          ctx.textBaseline = "bottom";
          // 绘制背景
          ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax);
          ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
          // 绘制文字
          for (let i = 0; i < this.identifyCode.length; i++) {
              this.drawText(ctx, this.identifyCode[i], i);
          }
          this.drawLine(ctx);
          this.drawDot(ctx);
      },
      drawText(ctx, txt, i) {
          ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
          ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + "px SimHei";
          let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
          let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
          var deg = this.randomNum(-20, 20);
          // 修改坐标原点和旋转角度
          ctx.translate(x, y);
          ctx.rotate((deg * Math.PI) / 180);
          ctx.fillText(txt, 0, 0);
          // 恢复坐标原点和旋转角度
          ctx.rotate((-deg * Math.PI) / 180);
          ctx.translate(-x, -y);
      },
      drawLine(ctx) {
          // 绘制干扰线
          for (let i = 0; i < 3; i++) {
              ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax);
              ctx.beginPath();
              ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight));
              ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight));
              ctx.stroke();
          }
      },
      drawDot(ctx) {
          // 绘制干扰点
          for (let i = 0; i < 50; i++) {
              ctx.fillStyle = this.randomColor(0, 255);
              ctx.beginPath();
              ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI);
              ctx.fill();
          }
      },
  },
  watch: {
      identifyCode() {
          this.drawPic();
      },
  },
  mounted() {
      this.drawPic();
  },
};
</script>